A vehicle door smart key system (registered trademark) has become widespread in recent years. E.g., the following technique (Patent Document 1) has been proposed as this type of system. In this technique, when a door lock is released or locked by a door lock releasing signal or door lock locking signal emitted by a portable device (smart key), a light-emitting diode is lit for a predetermined period, informing a driver of the door lock status. Specifically, when the door lock is released, a red light-emitting diode embedded in a door handle having a transparent body is lit for a fixed period, and when the door lock is locked, a green light-emitting diode embedded in the door handle having the transparent body is lit for a fixed period. In this technique, power supply to the two-color light-emitting diodes is performed by magnetic coupling. Consequently the handle, does not become unsightly even if it consists of transparent material, and the waterproofing treatment needed when wiring is mounted becomes unnecessary.